Environmental degradation of some polymer blends. Blends of polystyrene with acrylonitrile butadiene styrene,poly(vinyl chloride), and polybutadiene and blends of polybutadiene with poly(vinyl chloride)

One class of polymer/additive which has become increasingly important is polymer blends. In this study the ultimate tensile strength, elongation at break, and the modulus of acrylonitrile–butadiene–styrene, poly(vinyl chloride), polybutadiene and polystyrene and their blends have been studied over an entire binary composition range. We have correlated these mechanical properties to their degradation behavior under natural and accelerated weathering by measurement of various indices during thermal and natural weathering. It was found that during natural weathering the presence of polystyrene in acrylonitrile–butadiene–styrene (ABS) improved the weatherability of ABS; the converse was true when the blends were heated in an air oven at 100°C. It was also found that the weatherability of PB was improved in the presence of polystyrene and large improvement in the rigidity was observed. Similarly, from a measurement of carbonyl index, it was found that PVC has a stabilizing effect on PB. In many cases, the 50:50 composition of the polymers gave the best compromise of good mechanical properties, heat stability, and outdoor weathering. The mechanisms of possible interactions between the degrading polymers are discussed.